Stringer EW lathe

[Michael GilliganParticipant @michaelgilligan61133]

Alan [and everyone interested]

You have hit upon one very important point, that merits further discussion.

For the EW fine feed … Do you want it "Independent" or "Synchronised" ?

The Exactus is Synchronised, as is any geared drive; but there have been several successful designs for Independent fine feeds.

MichaelG.

If we opt for Synchronised, it could eventually be developed into an "Electronic Leadscrew" for Screwcutting. … But let's walk before we try running.

[alan smith 6Participant @alansmith6]

Michael & EWers

I hope that you will have time to answer my post. It`s important that we have a clear idea of what we have to do. For the feed that will be linked to the spindle speed, which you call "synchronised", my feeling is that is the way to go, as it will be easier to control as one will not have to think about what feed to apply as this is already set up, and if the rate of feed can be adjusted whilst in motion a twiddle of a knob will give a slower or faster feed as required.

alan

[dcostaParticipant @dcosta]

Hello Neil,
Sorry for answering your message so late.

At 2012.08.22 you wrote:
You also need to pick up 'Ned' and 'ETW' and "Westbury' and probably other search terms as well. – a man
with one pen-name for each of his (many) areas of interest.

The first time I read this message I thought (because of my poor domain of your language) that you were making a little jock.
A second read told me that perhaps it was a suggestion rather than a jock.
A third reading make me be sure it was really a suggestion.
By this interpretation, I am sorry.

Now answering your suggestion:
The query I made had the sole criterion of ' EW ' in the title. Meaning that doesn't matter who is the author.
If I use OR as the logical operator with ' EW ' as criterion also in the notes I found one more article title "Bottled gas" and with note "Stuart No 4 and Sirius engines made on a 2 1/2' EW lathe".

Best regards
Dias Costa

[dcostaParticipant @dcosta]

Hello Alan Smith 6

Can this reversal be controlled manually? This is to do away with the complication of micro switches or their modern equivalent.
In my experience, a stepper motor stops rotation (not even a step more…) as soon as the power is cut.

Best regards
Dias Costa

[dcostaParticipant @dcosta]

Hello,

In my opinion it's a pity if this project stops at fine feeding a lathe.
At least it should keep the door open to go further to screw cutting and also as Mr. IanT suggested to control a rotating table .
There's a thread **LINK** and a product **LINK** called ELS. Information on both links may be a source of usable knowledge for this project.

Has anyone considered the possibility of using Raspberry pi or Arduino as the source of logic signal to the driver?
They are cheap (Raspberry pi: Total inc VAT and shipping = £31.86 , Arduino: £46 ) both are programable, the first is a highly meritory initiative, etc.

Obtained information for Raspbery pi price from here **LINLK**
Obtained information for Arduino price from here **LINK**

Usual disclaimer.

Best regards
Dias Costa

[alan smith 6Participant @alansmith6]

Hi Dias & EWers,

Looked at the links in your post and can see that this ELS group is still struggling with the screwcutting/ feed problem and the controller size is simply out of proportion to our tiny lathe. Unless MichaelG can come up with a simple solution then it`s back to the drawing board and a mechanical solution.

Alan

[dcostaParticipant @dcosta]

Hello Allan 6 & Ewers and others,
 

Unfortunately I don't know the EW lathe, so my appreciation of relative dimensions is poor.

The reference to the ELS product has only, as I said, the purpose of, eventualy, taking them as a source of information. Not to be followed as a model, and, I must stress, specialy not in size.

Adding some information to my previous message:
Both the Raspberry and Arduino are 105mm x 55mm . A little more in length than the size of a credit card.

For a simpler solution, not programable by itself, there is a simpler driver from Quasar electronics (**LINK**) that I use in my milling to drive the X axis table. Apparently the available board is a more recent version than mine.

It's dimensions are 80mm x 50mm x 22mm and you can directly control the voltage, the rotation direction and stop/start and its price is aroung £25.
It is called “3179 – Standalone / computer controlled unipolar stepper motor driver”.
The use of this driver keeps the door open for a more evolved and powerful version, eventualy usable for screwcutting or dividing, since it accepts external commands.

Best regards
Dias Costa

 

Edited By dcosta on 29/08/2012 15:00:31

[alan smith 6Participant @alansmith6]

Dias & EWers,

I looked at your milling table drive photos and there is probably some of the answers to our problem contained in them, although it does not synchronise with the spindle as in our case. Can you tell us what stepper motor you used and the available torque? is it easy to change direction and is the potentiometer used to increase the voltage and therefore the speed of the motor?

What is the power source is it a standard item that you can buy?

No disrespect to you Dias, your layout is typical of an amateur such as myself with the components exposed and the control of the motor done directly from the board. Is it possible to have the controls remote from the board so as to make the whole thing more tidy and presentable.

Alan

[Michael GilliganParticipant @michaelgilligan61133]

Posted by alan smith 6 on 29/08/2012 11:57:26:

Michael & EWers

I hope that you will have time to answer my post. It`s important that we have a clear idea of what we have to do. For the feed that will be linked to the spindle speed, which you call "synchronised", my feeling is that is the way to go, as it will be easier to control as one will not have to think about what feed to apply as this is already set up, and if the rate of feed can be adjusted whilst in motion a twiddle of a knob will give a slower or faster feed as required.

alan

Alan,

Please forgive me if I appear to be preaching … that is certainly not my intention, but I do have an important point to make:

You say: "… a twiddle of a knob will give a slower or faster feed as required."

Now, "twiddle of a knob" is a very Analog phrase, and I think we should be thinking exclusively Digital. … It is possible to mix the two, but it tends to be complicated and/or expensive.

The A3983, as implemented in the JAFmotion MicroStep, does everything that we NEED to emulate the Exactus Ratchet System [and more].

Straight out of the box, it offers:

• Drive Current of 1.2A per phase [which should be adequate]
• Switchable Forward/Reverse [whilst the system is running]
• Switchable Step-Mode [whilst the system is running]
• Step-Modes equivalent to 1/1, 1/2, 1/4, 1/8 Gearing
• Virtually instantaneous Stop

The wiring is extremely simple and we do not need an additional computer to drive it.

Hope that makes sense

I will answer your other points in my next posting.

MichaelG.

[alan smith 6Participant @alansmith6]

Thank you Michael,

You have to understand that my Knowlege base is analogue, so until I learn more about the digital world I can only relate things to analogue. You are not preaching and I`m willing to learn.

Alan

[Michael GilliganParticipant @michaelgilligan61133]

Posted by alan smith 6 on 29/08/2012 10:24:57:

Responses inserted in-line, for convenience … MichaelG.

 

Ian & Michael,

I think that we already are participating in an open source design project, the cross fertilisation of ideas is always beneficial.

Agreed, but I was hoping that David Clark might see fit to "sponsor" the project by setting-up some better environment than a forum thread.

What this thread is leading up to is a common direction for our endeavours. For the torque measurement probably IanT is the person most enabled to do this, as unlike myself, he has a working lathe, so what about it Ian, can you do this for us?

I cannot answer for Ian, but it should be fairly simple to do … put a flat-belt pulley on the end of the leadscrew, wind a few turns of cord around it, add weights until it drives the saddle.

Michael, you gave us a lot of information in your posting which, alas, I was unable to immediately comprehend, I will have to do a crash course in stepper motors and their control.

I will post links to some relevant sites … but frankly; unless you are interested in this for its own sake, don't bother! Just accept that some very clever people have put all the difficult stuff onto a tiny chip.

Ian put his finger on the essence of what we want, which is a simple deign for the feed only. not full CNC.

I hope I have addressed that point adequately already.

In order to help myself and probably others, I will put down my expectations from the stepper drive and let MichaelG tell us whether my expectations can be fulfilled. Then we can get down to the nitty gritty of the design itself.

From my experience in Procurement … please let's have the "Must" features clearly differentiated from the "Nice to have".

Firstly to see whether we need a leadscrew clutch, can the motor be instantly reversed? If it can, then we could probably do away with the clutch.

Please see previous post.

Can this reversal be controlled manually? This is to do away with the complication of micro switches or their modern equivalent.

Please see previous post … the switch can be fully manual if you wish.

To get the feed relative to the spindle speed, I assume that there will be some kind of optical device mounted on the headstock somewhere which sends a signal to the control box for the motor. This feed rate would be around .002" per rev of the spindle, which would be approximately 6 degrees of rotation of the leadscrew but I would expect that this rate of feed to be immediately adjustable to suit the type of material being machined.

Optical / Mechanical / Hall-Effect / etc. take your pick. "I would expect that this rate of feed to be immediately adjustable to suit the type of material being machined." … Why? it is not so on the Exactus version … see my earlier comment about specification.

In my experience simplicity is king and I see in my imagination that the motor would be controlled just like a model train set. All we would need is a forward, stop and reverse switch to control the feed with another rotating switch to control the speed of the feed. Perhaps we should choose a motor with more torque than initially deemed necessary, so that we would then need a way of controlling the torque of the motor.

Please see my previous posting … This is very important.

All one would have to do is to set the spindle speed, switch on and bring the tool to the work by means of the leadscrew handle, set the cut and then switch on the feed. At the end of the cut the feed would be stopped and either reversed at a faster rate by the motor, or reversed using the leadscrew handle.

There you are Michael, can this be done?

Yes.

Alan

 

 

Edited By Michael Gilligan on 29/08/2012 17:53:40

[dcostaParticipant @dcosta]

Allan Smith 6 & Ewers and others,

I looked at your milling table drive photos and there is probably some of the answers to our problem contained in them, although it does not synchronise with the spindle as in our case.
That's why I referred in a previous message the necessity/convenience of some more, simple or complex, electronics to provide pulses (1, 2, 3, n pulses by a revolution of the spindle).

Can you tell us what stepper motor you used and the available torque?
For motorizing the X axis of my milling BF20 I made some experiments with stepper motors, first from salvage and then from Arc Euro Trade (AET).
Soon I put the salvaged motors aside because for most of them there was not any information. Also, fearing the risk of not finding an equal motor in case of failure, made me chose AET motors. Their price is acceptable for my purpose.

Firstly I experimented a motor from AET ref. 160-010-00200 having the torque of 180Ncm. Its power was perfectly enough to drive the BF20 table. However after awhile I experimented with a more powerful motor 220Ncm, also from AET (ref. 160-010-0400) having the torque of 220Ncm.
There's another stepper motor less powerful also from AET (160-010-00100) having the torque of 36Ncm.
Just as an opinion, I think that the stepper motor having 180Ncm torque is enough and a good acquisition

is it easy to change direction and is the potentiometer used to increase the voltage and therefore the speed of the motor?
Yes it is. In one of the boards I have (I bought two), a friend of mine, after removing the original onboard potentiometer, applied an external one with two cables soldered on the board, and also applied a small resistance just to allow me to control the voltage remotely. Problem is, the potentiometer and resistance used were the ones I had at hand, not the most adequate. So the outside voltage control never was tested as it should and I am using now a new driver.
The change of direction may be done whilst the system is running.

What is the power source is it a standard item that you can buy?
I use two independent power sources. One for the logic (the board) and other for the motor.
The first is a mobile telephone charger.
The other is an 12Volt 3Amper common power source,

No disrespect to you Dias, your layout is typical of an amateur such as myself with the components exposed and the control of the motor done directly from the board.
Yes you are right. I'm always expecting to ameliorate the system but it never happens. And I already had problems caused by swarf. Had luck the board is robust and resisted to the swarf short circuiting some components.

Is it possible to have the controls remote from the board so as to make the whole thing more tidy and presentable.
Yes it is. You only need to de-solder the direction switch and the potentiometer and replace both by cables connected to the appropriate components.
There is one more switch to chose from inboard control or external control you must put in INT position.
To stop and start I use this switch but I think the best and correct way is to cut the power for the logic and for the motor simultaneously.

Hope I answered all questions you asked and my answers arte of some utility.

Best regards
Dias Costa

Edited By dcosta on 29/08/2012 18:17:27

[alan smith 6Participant @alansmith6]

Michael,

This area of knowlege is new to me and I haven`t yet learned all the jargon. As a boy I did an apprenticeship as a toolmaker and then went into the design office and since then my career has been in design engineering until I retired at the age of 70. As a design engineer it`s always important to try to understand the philosophy behind a concept.

One thing that I`ve picked up on is your question where you ask, why do I want to be able to change the rate of feed when it is not in the Exactus design.

From this I imagine that you are perhaps not so experienced in lathework. The Exactus design does not allow a change of feed unless the feed ratchet gear is changed! I supposed that with the stepper motor this could be done whilst the feed is in operation.

You realise that I have been trying to draw the information from you by putting down my thoughts on paper, so let`s see how you actually propose to carry out this design together with the switchgear and everything else to achieve the proposals that I have laid down without any jargon or acronyms and let`s see some sketches. Please accept this challenge

Alan

Edited By alan smith 6 on 29/08/2012 20:00:58

[alan smith 6Participant @alansmith6]

Dias & EWers,

I`m impressed by your command of English, thank you for your response, you have helped to make clear to me what this is about. I have asked MichaelG to provide us with a full design for the EW project as he seems so knowledgeable, then we will be able to judge whether digital or mechanical is the way forward.

Edited By alan smith 6 on 29/08/2012 19:57:03

[Michael GilliganParticipant @michaelgilligan61133]

Posted by alan smith 6 on 29/08/2012 19:45:01:

Michael,

This area of knowlege is new to me and I haven`t yet learned all the jargon. As a boy I did an apprenticeship as a toolmaker and then went into the design office and since then my career has been in design engineering until I retired at the age of 70. As a design engineer it`s always important to try to understand the philosophy behind a concept.

One thing that I`ve picked up on is your question where you ask, why do I want to be able to change the rate of feed when it is not in the Exactus design.

From this I imagine that you are perhaps not so experienced in lathework. The Exactus design does not allow a change of feed unless the feed ratchet gear is changed! I supposed that with the stepper motor this could be done whilst the feed is in operation.

You realise that I have been trying to draw the information from you by putting down my thoughts on paper, so let`s see how you actually propose to carry out this design together with the switchgear and everything else to achieve the proposals that I have laid down without any jargon or acronyms and let`s see some sketches. Please accept this challenge

Alan

Edited By alan smith 6 on 29/08/2012 20:00:58

 

.

Sorry Alan … I have enough "challenges" on my list already; and I thought we had decided that this had the makings of a collaborative project.

You say [above] … "One thing that I`ve picked up on is your question where you ask, why do I want to be able to change the rate of feed when it is not in the Exactus design.

From this I imagine that you are perhaps not so experienced in lathework. The Exactus design does not allow a change of feed unless the feed ratchet gear is changed! I supposed that with the stepper motor this could be done whilst the feed is in operation."

.

Although not professionally trained, I do have plenty of experience in Lathework, thank you … and I am perfectly aware that a range of feed rates is desirable. … What I was trying to find out was whether this was on the "Must" list, or the "Nice to have" list. … You are, after all, starting from a baseline of the Exactus design, but you stated: "I would expect that this rate of feed to be immediately adjustable to suit the type of material being machined."

 

I have offered a suggestion … but will now hand it over to the forum

[quote] … let`s see how you actually propose to carry out this design together with the switchgear and everything else to achieve the proposals that I have laid down without any jargon or acronyms and let`s see some sketches. Please accept this challenge … [/quote]

 

Quite simply, Alan; I do not "propose to carry out this design < etc. >" … I do not have an EW, and have no particular interest in the machine-specific detailing. … so it's over to you chaps.

I genuinely wish you every success.

MichaelG.

 

Edited By Michael Gilligan on 29/08/2012 21:51:37

[alan smith 6Participant @alansmith6]

I called your bluff michael! why do you contribute to a thread if you do not want to go the distance?

Edited By alan smith 6 on 29/08/2012 22:21:57

[Michael GilliganParticipant @michaelgilligan61133]

Out of a genuine desire to help others where I can!

… I played no bluff … I simply made a suggestion.

MichaelG.

[Michael GilliganParticipant @michaelgilligan61133]

As promised, earlier …

For those who may be interested in understanding Stepper Motors:

This is a good place to start

And this is the definitive reference

MichaelG.

[alan smith 6Participant @alansmith6]

Hi EWers,

If you have been following the thread then you will know that MichaelG has quit. There are folk that graze the threads, make comments but do not follow through. If I have misjudged Michael then I proffer my abject appologies,but if you look at his last posting (21.45) you may get an insight into his attitude to our EW lathe. Someone who has made 337 posts and submitted 20 photos (have a look at them) could be viewed as not being serious.

I am only concerned with our EW lathe for the reasons that you are all aware of. If any EW owner thinks that I have been unfair to MichaelG, then let it be known and I will cease contributing to this thread.

I will continue to design a mechanical solution for the slow speed and it could be said that this is the way that should be followed for the EW with respect to it`s origins.

However I am fascinated by the possibilities of digital control and look forward to a satisfactory solution. We never know the background of contributors to the thread and sometimes these contributions have to be taken with a pinch of salt.

I think that the way forward now will be to put the design into the hands of one of the suppliers technical departments, then at least we will know that the design will be handled professionally.

Alan

Edited By alan smith 6 on 29/08/2012 23:58:23

[jason udallParticipant @jasonudall57142]

Alan.

I do not know (beyond your postings) either you or michael

I also do not know The EW.

Or the problem/challenge being discussed..

Thus I cannot suggest other than in general terms anything.

1. the stepper motor solution for a screw cutting gear train ..might be simple enough to have merit (works for cnc)..

2. as to powerfeed …"simiple knob for speed switch for direction"…certainly do able…

Much the same hardware for both..

things to note..ungeared stepper motors when unpowered have little or no resistance to movement..so could quite happilly remain coupled when using lead screw in "manual"…

a pickup off the spindle giving a suitable number of pulses could drive the stepper drive board..( and with dividers in the path provide for the "change" wheel function and yes "on the fly" whilst in motion)

In anycase whether a purely mechanical or electro mechanical solution is "BEST" would depend on individual taste…

[IanTParticipant @iant]

Hi everyone, perhaps it's time to slow down a bit.

There are some very interesting thoughts that have been contributed here and I'd like to thank Michael and Dias for their time and effort in helping us out. I have looked at the various links provided and several of these devices do seem (to me) to be a very good start to the generic device I had in mind – at least in terms of functionality. Enjoyed your photos Dias (with just a hint of jelousy) some very nice projects here that you've completed and your mill drive is very practical example of what I had in mind..

I will admit to not (quite) understanding how some of these smaller 'stepper' devices handle the stepper motor current requirements (heat etc) when other 'driver' boards (AET?) seem to be much larger – and just designed to step the motor with no degree of 'intelligence'. But there certainly is the core of a good idea there in there – Thank you Micheal for bringing them to my attention..

Personally, I'm in no great hurry to resolve these issues, I'm busy building my small milling head and (for a change) I am managing to stick to this one project – without getting dragged off to new delights at the drop of a hat. I'm afraid I do tend to have a Butterfly tendancy – 'fluttering' from one project to another as I get stuck (or bored) with the current job. So I'm trying to be good (focused) and actually complete the milling head in a fairly linear manner this time. A good discipline to practice occasionally!

Fortunately, it is my Hobby not my Living. So thank you again (everyone) for your input – all noted and hopefully all useful when I get around to focusing on this particular project sometime in the future.

Best regards,

Ian T

[Michael GilliganParticipant @michaelgilligan61133]

Posted by alan smith 6 on 29/08/2012 23:50:53:

if you look at his last posting (21.45) you may get an insight into his attitude to our EW lathe.

For the avoidance of doubt:

In my posting of 29/08/2012 21:45:44 … "machine-specific" was hyphenated.

I meant exactly what I wrote: " … no particular interest in the machine-specific detailing. "

Mr Stringer's lathe was an admirable design in many ways, and my "attitude" to it has always been positive.

MichaelG.

[Ian S CParticipant @iansc]

Unless I was going to hitch my lathe to a computor, I would proberbly power the feed the same way I power feed my mill, with a windscreen wiper motor, via a bit of bike chain, and a pair of sprockets. You could proberbly knock up something simple in a day in the workshop. Ian S C

[alan smith 6Participant @alansmith6]

Hi EWers,

Post deleted due to personnel comments about several members.

More comments like this will result in suspension for one week.

regards David

 

Edited By David Clark 1 on 30/08/2012 15:57:14

[alan smith 6Participant @alansmith6]

HI Ian S C,

Thank you for your posting, Can a wiper motor be reversed and what would be your solution to co-ordinate the spindle speed with the leadscrew speed. would there be a problem with the inertia of the chain, sprockets and motor rotor to prevent the assembly from stopping immediately, if so a clutch would be required.

Alan

Edited By alan smith 6 on 30/08/2012 12:56:28

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